High-dose vitamin C can affect which dipstick readings?

High-dose vitamin C can affect which dipstick readings?

• A. High-dose vitamin C can affect nitrite readings (and can cause false negatives in glucose, bilirubin, and blood tests).
• B. Vitamin C only affects leukocyte esterase.
• C. Vitamin C only affects protein.
• D. Vitamin C only affects urobilinogen.

Answer: (A)

High-dose vitamin C interferes with urine dipstick chemistry because ascorbic acid is a strong reducing agent that can alter color development in several test pads. The nitrite pad relies on a color change produced by the Griess reaction after bacteria convert nitrates to nitrites; ascorbic acid can chemically reduce nitrite or blunt the color change, leading to a false-negative nitrite result even when nitrite is present. In addition, the enzymatic and colorimetric reactions used to detect glucose, bilirubin, and blood can be dampened by excess ascorbate. The glucose pad depends on enzymatic reactions that generate a colored product, which can be suppressed by high levels of vitamin C. The bilirubin pad uses a diazo reaction to form a colored compound, which ascorbate can reduce or mask. The blood (heme) pad also relies on a colorimetric reaction that can be diminished by reducing agents like ascorbate. So high-dose vitamin C can skew nitrite readings downward and cause false negatives for glucose, bilirubin, and blood on dipstick testing.

High-dose vitamin C interferes with urine dipstick chemistry because ascorbic acid is a strong reducing agent that can alter color development in several test pads. The nitrite pad relies on a color change produced by the Griess reaction after bacteria convert nitrates to nitrites; ascorbic acid can chemically reduce nitrite or blunt the color change, leading to a false-negative nitrite result even when nitrite is present.

In addition, the enzymatic and colorimetric reactions used to detect glucose, bilirubin, and blood can be dampened by excess ascorbate. The glucose pad depends on enzymatic reactions that generate a colored product, which can be suppressed by high levels of vitamin C. The bilirubin pad uses a diazo reaction to form a colored compound, which ascorbate can reduce or mask. The blood (heme) pad also relies on a colorimetric reaction that can be diminished by reducing agents like ascorbate.

So high-dose vitamin C can skew nitrite readings downward and cause false negatives for glucose, bilirubin, and blood on dipstick testing.